In order to download a large amount of data such as video data from a file server to a mobile terminal, there is a demand to maintain a stable, high-speed network connection between the mobile terminal and a base station. However, if a communication rate in a network is not sufficient or communication is not executed in the network due to a restriction caused by congestion, a disease, or the like or due to the fact that the mobile terminal is located outside a communication area, it takes a lot of time to download the data or the data is not downloaded. In addition, a technique in which a mobile network communicates data requests to neighboring data stores and the neighboring data stores pre-fetch the data is known (refer to, for example, Japanese National Publication of International Patent Application No. 2011-525312).
In addition, since the amounts of traffic in communication carriers' lines for mobile terminals increase, there is a demand to take an off-load measure to cause traffic to travel to lines and the like other than the carriers' lines. For the measure, there is a method for accessing a file server through a wireless-fidelity (Wi-Fi) (registered trademark) access point that is able to be connected to mobile terminals. This method is referred to as Wi-Fi off-load and promoted in order to distribute traffic to base stations of carriers. In addition, an ad-hoc network technique for forming an autonomous network by causing mobile terminals to directly communicate with each other is known.